What is baby brain? Symptoms, causes and what the research says

So, what is baby brain, when does baby brain start and is baby brain a real thing? Here's what the latest science says.

Baby brain – sometimes called pregnancy brain or pregnancy brain fog – is a non-medical term used to describe changes in memory, concentration and mental clarity that some people notice during pregnancy or after having a baby. Many people report feeling more forgetful, finding it harder to focus or feeling mentally slower than usual, although experiences vary and not everyone notices these changes.¹

Although baby brain isn't recognised as a medical condition, it's a phrase that's widely used to describe a very real experience for many parents. Research into whether these changes can be measured objectively has produced mixed results. Some studies have found small changes in certain aspects of memory and thinking during pregnancy, while others suggest that disrupted sleep, stress, anxiety and the mental load of preparing for a baby may explain many of these experiences.^1,4

Current evidence suggests baby brain is probably influenced by a combination of hormonal, neurological and lifestyle factors, alongside the brain's natural adaptations as it prepares for caring for a baby. So far, scientists have found evidence that the brain undergoes changes during pregnancy that may support bonding with and caring for a newborn, although researchers are still learning what these adaptations mean in everyday life.

The important thing to remember is that occasional memory lapses during pregnancy or after birth are common and don't necessarily mean anything is wrong.

These changes can continue into the postnatal period when broken sleep, recovery and adjusting to life with a newborn may also affect memory and concentration. This is why some people describe experiencing post-pregnancy brain fog.³

One theory centres on the brain itself. In one landmark study,⁵ researchers found pregnancy was associated with long-lasting structural changes in parts of the brain involved in social cognition. More recently, a 2024 MRI study mapped changes in the brain throughout pregnancy, finding widespread remodelling across multiple brain regions as hormone levels changed. Rather than being harmful, researchers believe these adaptations may help parents recognise and respond to their baby's needs after birth, although they're still investigating exactly what they mean for memory and thinking. Hormonal changes may also play a role, alongside poor sleep, physical fatigue, stress and the mental load of preparing for a baby, all of which can affect attention and memory. ^3,5

Insomnia affects around a quarter of women in the first trimester, rising to around 40% by the third trimester.⁷ Good-quality sleep supports memory, concentration and overall wellbeing. While pregnancy can make sleep more difficult, sticking to a regular bedtime routine and resting when you can may help.

Eating a varied diet with plenty of fruit, vegetables, wholegrains, healthy fats and protein helps support your overall health during pregnancy. Nutrients such as choline, iodine and omega-3 fats are also important for your baby's brain development. While more research is needed into whether specific nutrients affect baby brain, eating a balanced diet helps support both your health and your baby's development throughout pregnancy.^8-10

If it's safe for you, regular exercise during pregnancy can support both physical and mental wellbeing. Even gentle activities like walking or prenatal yoga can help.

Growing a baby is physically and mentally demanding. Using reminders, keeping a diary or writing lists can help take some of the pressure off if you're feeling more forgetful than usual.

Although baby brain isn't a medical diagnosis, many people recognise the experience it describes. Looking after your overall wellbeing, getting as much rest as possible and giving yourself a little grace can all help while your body adjusts to pregnancy and early parenthood.

If you're looking for more ways to support your wellbeing during pregnancy, explore our guides to pregnancy nutrition, brain health and the importance of omega-3.